The maximum bandwidth would be twice as high, but the point SKYMTL was making is that even a PCI-E 2.0 x8 is the same as PCI-E 1.1 x16, and the latter has yet to be (properly) demonstrated as being a bottleneck to any high-end graphics cards. Thus, using a P45 chipset should pose no issues when running Xfire setups using 4850/70 cards. The X2 cards... well, hard to say at this point.

The maximum bandwidth would be twice as high, but the point SKYMTL was making is that even a PCI-E 2.0 x8 is the same as PCI-E 1.1 x16, and the latter has yet to be (properly) demonstrated as being a bottleneck to any high-end graphics cards. Thus, using a P45 chipset should pose no issues when running Xfire setups using 4850/70 cards. The X2 cards... well, hard to say at this point.

I totally understood that before, but my question was more like towards choosing an X48 mobo or P45 mobo, so since x48 has pci-e 2.0 slots running at 16x and p45 has them at 8x, would I see a huge performance difference in crossfire.

I totally understood that before, but my question was more like towards choosing an X48 mobo or P45 mobo, so since x48 has pci-e 2.0 slots running at 16x and p45 has them at 8x, would I see a huge performance difference in crossfire.

Our point is: no, you wouldn't. This is because today's cards are nowhere NEAR close to passing the bandwidth offered by an 8x PCI-E 2.0 slot. No matter what Tweaktown would like you to think.

Our point is: no, you wouldn't. This is because today's cards are nowhere NEAR close to passing the bandwidth offered by an 8x PCI-E 2.0 slot. No matter what Tweaktown would like you to think.

Until you can provide evidence on the contrary then I can't believe your words of advice considering that tweaktown has conducted the tests on both platforms which contain PCI-E 2.0 on each slot. You can consider the results to be propaganda but, here is another site that has done tests using 2 4850 cards on dual PCI-E 2.0's as well...

Even in that review all tests between Crossfire solutions on PCI-E 2.0 boards are WELL within the margin of error. Run any of those benchmarks used 5 times and you will probably get 5 different results. That is why many sites out there (this one included) use AVERAGES of 3 or more benchmark runs.

I am not sure about LH's methodology but it doesn't mention anywhere how they tested each game.

As I mentioned, these differences can even be chalked up to the variances between one motherboard and another as well. Check reviews which pit one X38 against another and you will see benchmark scores which are quite a bit different from one game / synthetic benchmark to the next. This has NOTHING to do with PCI-E bottlenecking but rather how one board may perform slightly differently than another.

I agree 100%. I have both P45 and X48 boards and the results are very close if not identical with 3870 in CF. I attribute the slight differences to margin of error and difference in motherboard performance (chipset latency, secondary mem timings, etc). 4850 may be a little different but 2 FPS is hardly proof of anything.

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